A device may incorporate a variety of technologies for providing haptic feedback, including active and/or resistive technologies. Active haptic feedback devices, including for example, motors, generally add energy to a system. Resistive, or passive, devices, such as brakes, generally remove energy from a system.
Resistive haptic feedback devices often rely on friction to output a haptic effect to a user. Materials used in such a device may wear prematurely or unevenly as a result of friction between moving elements. A coefficient of friction between such moving elements may change over time as a result of this wear. The performance of a resistive haptic feedback device may be altered by wear caused by friction.
Some attempts to minimize some of these deleterious effects of friction have focused on the use of lubricants. Lubricants, however, may not be desirable for several reasons. Some lubricants may mitigate, and in some circumstances alter, desired haptic effects. Some lubricants deteriorate over time, and require replacement. Additionally, the addition of lubricants adds to the cost of manufacturing, operating, and maintaining certain devices.
These, and other, attempts to overcome problems associated with friction have been less than entirely successful, and their utilization in devices have produced somewhat unsatisfactory results for users.